Birthdays and anniversaries are popular choices on lottery tickets, so when the six main numbers in last Saturday's draw were all below 31, more than 219,000 people matched three numbers.

That was a 60% increase over a typical Saturday, and the bonanza caused havoc with the overall prize fund, with each of those players guaranteed a £25 prize.

As a result, the 16,500 people who matched four numbers received just £15 pounds each, creating some angry customers.

Lottery Rip Off I received £10.00 less for getting an extra number? 3 numbers I would receive £25.00 but silly me I got four and got £15.00?

— Ricky Swannell (@Brashland) August 14, 2014

The two jackpot winners could also have considered themselves unlucky, despite overcoming 1 in 14 million odds to get six numbers.

The won £360,000 each, compared to the average jackpot of more than £2m.

Camelot said the £25 'Match 3' prize sometimes works to the advantage of people who get more than three numbers.

A spokesman said: Â"In last weekÂ's Lotto draws, a lower than expected number of Match 3 winners resulted in higher than estimated jackpots and increased prizes at the other levels.Â"